1. Field of the Invention
The present invention relates to a vaporized liquid fuel combustion apparatus and more particularly to improvement of or relating to a vaporized liquid fuel combustion apparatus of the type including a cylindrical combustion chamber, a blower, an end plate located between the combustion chamber and the blower and a heat exchanger for heating fluid by utilizing thermal energy generated in the combustion chamber.
2. Description of the Prior Art
To facilitate understanding of the present invention it will be helpful that a typical conventional vaporized fuel combustion apparatus of the above-mentioned type is described below with reference to FIG. 1.
As illustrated in the drawing, the combustion chamber 10 is formed in a cylindrical configuration and includes an end plate 12 at the downstream end, an end plate 14 at the upstream end and a flame orifice 16 located in the middle part thereof each of which is fixedly secured to the combustion chamber 10 by welding. The upstream end plate 14 is formed with an air inlet port 17 through which combustion air is introduced into the combustion chamber 10 and moreover includes a shielding plate 18 which serves to inhibit combustion air from flowing straight without any hindrance encountered. Since the shielding plate 18 is exposed to the elevated temperature of combustion gas during operation of the apparatus, it is a component which deteriorates within a very short period of time. A heat exchanger 20 having an annular air passage is fixedly secured to the outer periphery of the cylindrical combustion chamber 10 by welding. Further, the combustion chamber 10 has an ignition plug mounting sleeve 24 fixedly secured thereto by welding so that an ignition plug 22 is threadably mounted on the ignition plug mounting sleeve 24. The inner wall of the ignition plug mounting sleeve 24 is lined with a layer of firing wick 28 which absorbs liquid fuel delivered via a fuel pipe 26 to maintain the flame in the combustion chamber. The firing wick 28 is one of the components which deteriorate within a short period of time and, therefore, must often be replaced with a new one.
An air introducing apparatus for introducing combustion air into the combustion chamber 10 essentially comprises a casing 32, a motor 34 and a rotor 36 driven by the motor 34. The casing 32 is formed with an air duction port 38 and a discharge port 40. As the rotor 36 is rotated, air is discharged from the air discharge port 40 to be introduced into the combustion chamber 10 through an air inlet port 17 on the upstream end plate 14. Combustion gas generated in the combustion chamber 10 enters the heat exchanger 20 via a communication passage 42 and it is then discharged to the outside via a discharging pipe 44 which is connected to the outer wall of the heat exchanger 20.
On the other hand, the motor 34 is operatively connected to a blower fan 46 for supplying air to be heated and air to be heated flows along the inner wall of a cover 48 in the direction as identified by double-lined arrow marks in the drawing.
As is apparent from the drawing, the combustion chamber 10 is made integral with the heat exchanger by welding and the end plate 14 with a combustion inlet port formed thereon is fixedly secured to the upstream end of the combustion chamber 10 by welding. (It should be noted that the conventional vaporized liquid fuel combustion apparatus as constructed in the above-described manner is disclosed, for instance, in Japanese Publication Patent No. 5685/1962.) The arrangement of the conventional apparatus made in that way makes it impossible to replace an individual component, for instance, shielding plate 18 with a new one or to repair it when it deteriorates under the influence of elevated temperature. Accordingly, a drawback of the conventional apparatus is that the service life of the combustion chamber 10 and the heat exchanger 20 is limited by the service life of components which deterisrate within a short period of time. Another drawback is that manufacturing of the conventional apparatus requires many man-hours for performing welding due to the fact that the combustion chamber is made integral with the heat exchanger by welding. As a result, the apparatus is manufactured at an expensive cost. Further, since the apparatus is constructed such that the combustion chamber 10 is fixedly secured to the one side of the casing and the support plate 49 for the motor 34 is fixedly secured to the other side of the same, it requires many man-hours for assembly, resulting in increased manufacturing cost.